Okay, that makes sense. :) On Friday, March 28, 2025 at 1:41:26 PM UTC+1 José Valim wrote:
> Thanks for the proposal. > > The difference between assert_receive to assert_wait, if my understanding > is correct, is that assert_receive is based on messages, while assert_wait > is a busy loop (i.e. you keep retrying after some time until it succeeds). > And the reason we haven't added something similar to Elixir is because you > should prefer message driven loops as much as possible, and we should > strongly nudge people towards solutions like assert_receive. > > > *José Valimhttps://dashbit.co/ <https://dashbit.co/>* > > > On Fri, Mar 28, 2025 at 1:10 PM David Pavlík <d.p...@gmail.com> wrote: > >> Hi! >> >> >> In our codebase, we use a macro called assert_wait that behaves like >> assert but retries if it fails until some timeout is exceeded. If the >> timeout is reached, it raises in the same way as a failing assert would. >> >> >> We've been using it for about a year and are quite happy with it. We find >> it very convenient for testing asynchronous behaviors in integration tests. >> For example, when you tell some process to asynchronously do something, you >> can then use assert_wait to check that the process has done it and done >> it correctly. It can also act as a synchronization mechanism as it “pauses >> execution” of the test until the given condition holds. >> >> >> Example: >> >> >> test "input is correctly processed by the processing pipeline" do >> >> input = ... >> >> expected_output = ... >> >> >> {:ok, ref} = PipelineManager.start_pipeline(input) >> >> assert_wait %{status: :finished, output_file: output_file} = >> PipelineManager.get_info(ref) >> >> assert expected_output == File.read!(output_file) >> >> end >> >> >> >> Of course, testing based on timeouts is not ideal. If you set the timeout >> too low or if the machine is currently under heavy load, the timeout may be >> exceeded even when everything is going well so far. However, sometimes >> there are no easy alternatives. It’s similar to assert_receive/3 or >> Phoenix.LiveViewTest.assert_redirect/2 that also have a timeout (though >> based on receive and not retrying). >> >> >> Do you think it would be generally useful to have something like this in >> ExUnit? If so, I can tidy the code a bit and send a PR. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "elixir-lang-core" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to elixir-lang-co...@googlegroups.com. >> To view this discussion visit >> https://groups.google.com/d/msgid/elixir-lang-core/d0e3cadf-50fb-4c66-a7d8-31feda17b9cfn%40googlegroups.com >> >> <https://groups.google.com/d/msgid/elixir-lang-core/d0e3cadf-50fb-4c66-a7d8-31feda17b9cfn%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-core+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/elixir-lang-core/b219446e-e483-4db7-b444-737f41df2233n%40googlegroups.com.
